1. Field of the Invention
The present invention relates to oil and gas well drilling and blow out preventor systems associated generally with oil and gas well drilling, and more particularly, the present invention relates to the detection of leaks from a blow out preventor at the wellhead. Even more particularly, the present invention relates to an apparatus for the detection of leaks from fittings at the blow out preventor and the subsequent collection and usage of the leak pneumatically to trigger an instrumentation system for valve closure, alarm actuation or the like.
2. General Background
In the drilling of oil and gas wells or in the subsequent production of oil and gas after drilling, a well is normally equipped at the wellhead (i.e., the top of the well) with a device which prevents the catastrophic uncontrolled release of oil and gas from the well as occurs when the well comes in too rapidly, or when high pressures within the well are released to the surface in an uncontrolled fashion. This abrupt release of gas from the well is known as a "blow out" condition. Devices are commercially available to close the well off at the wellhead to prevent damage or injury or loss of the well under such conditions. Such devices are known in the oilfield generally as "blow out preventors", or in oil field terminology sometimes this is shortened to the term "B.O.P." or "B.O.P. stack".
A blow out preventor or "B.O.P." or "B.O.P. stack" is typically a device which is fastened to the well at the surface or "wellhead" and which is used in a manual or automatic fashion to close off the well bore in order to trap high pressurized fluids from escaping. A blow out preventor is normally an outside device as opposed to an inside B.O.P. which might be run in the well or casing itself. An outside B.O.P. is typically comprised of an outside housing which provides on its inside one or more "rams" which are, for example, hydraulically driven, typically paired cooperating closures that proceed from an outer lateral position inwardly along a common horizontal plane until they meet at a sealing position at which the rams cooperate with their mating faces forming a closure of the well bore. Thus, there is prevented an uncontrolled escape of fluids from the well bore which can be catastrophic and lead to explosion, fire, injury, death as well as property damage. Rams which are part of the blow out preventor can have indentations to conform to the exterior of the drill pipe, or can be merely flat on their mating surfaces so as to cut the pipe in half upon closure, to seal the well. These latter rams are called shear or blind rams, whereas those with indentations to fit about the drill pipe so as not to damage it are known as pipe rams. There can also be provided in many cases an annular preventor at the uppermost portion of the B.O.P. stack. The term "stack" is used because different types of ram assemblies are assembled together, one above the other, in such a fashion as to provide a "stack" of the various rams to the overall blow out preventor system. The assembly of the blow out preventor and its attachment to the wellhead necessarily provides a plurality of fittings such as, for example, flanged connections which might be bolted, for example, and which because of their assembly produces sealed interfaces which are subject to leakage upon failure of the seal. It will be appreciated that leakage though these flanged or like connections are unaffected by the rams which comprise the sole means of closure of the wellbore in the event of a blow out condition. Thus, while the various pipe rams, blind rams, and shear rams may form an inside closure within the housing of the B.O.P. stack to the escape of high pressurized fluids from the well bore, it will be appreciated that leakages through the flanged or other connections of the blow out preventor will not be closed and and thus a catastrophic leakage or explosion could occur as gas or the like escapes through these connections where a leak exists. It is to this problem that the present invention is directed.
The present invention solves these problems by providing a means for collecting any leakage through the B.O.P. stack and especially at the connection portions and flanges where seal failure occurs. The collected leak is used as instrumentation fluid to pneumatically or fluidically operate a desired instrumentation system to indicate the presence of a leak, sound an alarm, actuate a valve closure or the like or for that matter perform any other task which could be done once accumulated pressure were available for such instrumentation purposes.
The present invention provides a capsule which forms an envelope about the flanged connection or other point of assembly of the B.O.P. stack which might be "suspect" of leakage. It should be understood that the term "suspect" would generally indicate any portion of a B.O.P. stack which might produce an external leak. This could be a flanged condition, for example, or any other interface of two separate parts on the B.O.P. stack which relied upon a perfect seal in order to keep leakage from occurring.
The capsule would be assembled in a sealable fashion about the suspect area of the B.O.P. stack forming a seal thereabout with the enveloping capsule so positioned collecting any leakage therewithin. The leakage would be transmitted through a provided annular collecting space to a regulator affixed to, for example, the wall of the capsule where the accumulated leakage could be used as instrumentation fluid to pneumatically actuate a regulator to perform any desired instrumentation task such as the closure of a valve, the sounding of an alarm, or the like. The use of such a regulator for the purpose of instrumentation responsive to the accumulation of a leak is discussed generally in my prior U.S. Pat. Ser. No. 4,232,736 which is hereby incorporated by reference, of which the present application is a continuing application.
The present invention thus provides an automatic remotely operable leak detection system for use with blow out preventors.
It is thus an object of the present invention to provide a leak detection and safety monitoring system for use with blow out preventors which senses and operates responsive to leakage from the blow out preventor to the exterior thereof.
It is another object of the present invention to provide a leak detection system for use with blow out preventors wherein the leak from the system itself provides usable instrumentation fluid for operation of the apparatus.
Another object of the present invention is to provide a leak detection system for use with blow out preventors which is simple to construct, easy to maintain, and easy to use.
Another object of the present invention is to provide a leak detection system for use with blow out preventors which is highly versatile, and which can be installed on different types of blow out preventors in a variety of applicatons including existing, in-use devices.
Another object of the present invention is to provide a leak detection system for blow out preventors which provides leak detection at the earliest occurrence of leakage therefrom.
Another object of the present invention is to provide a leak detection system for use with blow out preventors which can be easily adapted to a variety of instrumentation systems.